Its about Physiology of renal perfusion , perfusion pressure , Target MAP in septic shovk , recent evidences on renal perfusion , trials on target MAP in sepsis

1. - DR.Gowthaman.T.B. DM CCM
AIIMS BHOPAL
RENAL BLOOD FLOW AND
PERFUSION

2. OVERVIEW
BLOOD SUPPLY
PERFUSION PRESSURE
EFFECTS OF DRUGS , PPV ON KIDNEY
AUTOREGULATION
MY TARGET MAP
EVIDENCES

3. PARTS :
• Renal Cortex
• Renal Medulla ( Pyramids  Calyx )
• Renal Pelvis ( Calyx Hilus )
• Ureter

5. BLOOD SUPPLY

8. AORTA  RENAL ARTERY SEGMENTAL ARTERIES
INTERLOBAR ARTERIES ARCUATE ARTERIES
INTERLOBULAR ARTERIES
INTERLOBULAR VEIN ARCUATE VEIN INTERLOBAR VEINS
SEGMENTAL VEINS RENAL VEIN IVC
BLOOD SUPPLY

9. Countercurrent exchanger .
Decides the concentration of
urine .
Maintains HYPERTONICITY
VASA RECTA

10. RENAL BLOOD FLOW
• 1.2 Litre / Min
• 20 % of Cardiac output
• RBF  GFP  GFR
• GFR : 120 ml/ min / m ²
• RBF = RAP – RVP / RVR or P / R
• RVP : 2-4 mm Hg ( HF , IAP )

11. PERFUSION PRESSURE ( P )
DETERMINANTS :
1. MAP ( RAP)
2. Renal venous pressure

12. MAP - DETERMINANTS
• Systolic BP
• Diastolic BP
• SHOCK
 Sepsis , Cardiogenic , Obstructive,Hemorrhagic .
• Vasopressors .
• Hypovolemia .

13. • Venous congestion ( Thrombus , emboli , HIGH PEEP )
• Heart failure ( Right ) .
• SEPSIS  CVP  RVP  RPP  AKI .
• IA Pressure  Abdominal compartment syndrome ( 2
reasons ) .
RENAL VENOUS PRESSURE - DETERMINANTS
Compression of
vessels
Venous return
Cardiac output
Hypoperfusion

14. RIGHT HEART FAILURE
MCFP- RVP drops
RVP
RAP LOW C.O
NEURO HUMORAL
VASOCONSTRICTION
Hypoperfusion
AKI

15. EFFECT OF PPV ON RENAL PERFUSION
High PEEP ITP
Venous return drops
ADH ANF drops
H2o,Na retention
RVP
C.O
RENAL
PERFUSION
HAMPERED

16. PPV  REGIONAL REDISTRIBUTION OF
BLOODFLOW
DECREASES
INCREASES
Na,H2o reabsorbs
Urine drops

17. AUTOREGULATION

18. HYPERTENSIVE PATIENT – GFR

19. 2 MAJOR MECHANISMS :
1. MYOGENIC ( Aff Arteriole , IL arteries )
- Ability of vessels to resist wall stretching during
BP
2. TUBULOGLOMERULAR FEEDBACK
- Aff art + IL arteries are regulators .
Post Glomerulus vessels donot take part .

20. OTHER REGULATIONS ….???
NEURONAL : ( Noradrenergic SYMPATHETIC nerves )
1. Constriction of
Afferent art : GFR drops .
Efferent art : GFR rises .
HORMONAL :
1. Adenosine , NO
2. RENIN

21. MYOGENIC RESPONSE
Transmural pressure changes ( BP )
L – type Ca channel activation
Sensed by Smooth muscles
(AA,ILA)
Myogenic constriction
Aff arteriole Vaso constriction
Prevents excess stretch
Prevents excess
increase in GFR ,
RBF
FAST – 300 ms

23. TUBULOGLOMERULAR FEEDBACK
Na/ Cl delivery to Macula / RBF
Adenosine secretion
GFR , RBF
Vasoconstriction of Aff Arteriole
SLOW – 1 sec
PLAYERS :
1. ADENOSINE
2. NO

24. WHAT IS RAAS DOING ??

25. BP REGULATION
LOW BP
Afferent art
constriction
Adenosine
secretion
JGA
stimulation
Filtration rate
Less water loss
BP maintained

26. Still BP is low
RAAS activation
RENIN secreted
Na, H2o retention
BP maintained

27. • Vasodilators
• Prostaglandins
• Ca- channel blockers
• NSAIDS
• AMPHO-B
• Norad , vasopressin .
• Contrast
• Hypercalcemia
EFFECTS OF DRUGS IN ICU ON AFFERENT
ARTERIOLE :
AFFERENT CONSTRICTORS DILATORS

28. WHAT ABOUT ACE-I IN ICU ???
Ang-II
GHP
maintained

29. CAN AUTOREGULATION FAIL / ALTER ???
1. Chronic Hypertension  Right Shift
2. SEPSIS  Altered / Threshhold changes .

30. WHAT MAP SHOULD I TARGET TO MAINTAIN RPP ??
SSC GUIDELINES

31. ANY EVIDENCE ?
776 Patients - 2014 june
MAP 65-70 vs 80-85

34. Feb 2020 - 65 ICU – 2463 pts ( 3 years )
Std care vs MAP of 60-65 in > 65 yr old

36. • 2011  217 pts ( 3 years )
• 4 groups ( +/- AKI H6 , +/- Septic shock

38. SO WHAT MAP SHOULD I TRY TO MAINTAIN . . . . . .?

39. SHALL I SET A MAP and measure the
Kidney PERFUSION . . . .??
CLINICALLY  Urine output
LAB WISE  Creatinine

40. CAN I ACTUALLY MEASURE WHETHER MY
PATIENT´S KIDNEY IS GETTING ADEQUATELY
PERFUSED IN ICU . . . . . . .? ? ? ??

41. 2013 march – CCM journal

42. • Doppler
• Contrast CT
• MRI .
• Scintigraphy ( iodine )
• PET
• RCEUS ( microbubble )
• PAH Clearance .
• Microspheres ( Animal ) .
• Renal vein
thermodilution .
• Xenon washout
• IV doppler .
MEASURE !!!!
NON IMAGING IMAGING

43. BOLD –MRI

44. BEFORE
TERLIPRESSIN
AFTER
TERLIPRESSIN
RCEUS

45. 2018  pubmed .
20 patients – RCEUS
SHF4(sonovue)– contrast infusion use .

47. TAKE HOME
• Have in mind, the factors affecting Perfusion pressure in
our ICU
• AVOID drugs reducing RBF
• Have in mind how HIGH PEEP is going to affect GFR .
• TARGET MAP ?????  Still a MYTH .
• Higher MAP in Hypertensive patients .
• Can I try measuring RBF at bedside ???  Do Not waste
time .

48. REFRERENCE :
1.Critical care nephrology
2.Pilbeams
3.Up to date
4.Oh manual
5.Critical care Journals .

49. THANK YOU
for listening patiently……